Yang Y, Chen R, Zhou H M
Department of Biological Science and Biotechnology, Tsinghua University, Beijing, People's Republic of China.
Biochem Mol Biol Int. 1998 Jul;45(3):475-87. doi: 10.1080/15216549800202862.
The conformational changes of native and apo yeast alcohol dehydrogenase during thermal denaturation have been followed by fluorescence emission and circular dichroism spectra. A comparison of inactivation and conformational changes during thermal denaturation shows that for the native enzyme and for the apo-I YADH which has the conformational zinc removed, the extent of inactivation was larger than the extent of conformational changes at the same temperature. This result supported the suggestion by Tsou (Trends Biochem. Sci. 1986, 11, 427-429: Science 1993, 262, 380-381) that the enzyme active site is more flexible. The results also show that apo-I YADH without the conformational zinc was more easily inactivated with increasing incubation temperature, indicating that the stability of the apo-I YADH decreased. Kinetic analysis suggest that the substrate does not provide any protective effect during thermal inactivation of native and apo-I YADH.
通过荧光发射光谱和圆二色光谱跟踪了天然型和脱辅基酵母乙醇脱氢酶在热变性过程中的构象变化。热变性过程中失活与构象变化的比较表明，对于天然酶和去除了构象锌的脱辅基I型酵母乙醇脱氢酶（YADH），在相同温度下失活程度大于构象变化程度。这一结果支持了邹（《生物化学趋势》，1986年，第11卷，427 - 429页；《科学》，1993年，第262卷，380 - 381页）提出的酶活性位点更具柔性的观点。结果还表明，没有构象锌 的脱辅基I型YADH随着孵育温度升高更容易失活，表明脱辅基I型YADH的稳定性降低。动力学分析表明，在天然型和脱辅基I型YADH的热失活过程中，底物没有提供任何保护作用。
